Drug Therapy to Reduce Excess Estrogen
Estrogen is a growth-stimulating hormone. As stated earlier, fibroids typically shrink after menopause because of the reduction in endogenous (self-produced) estrogen that accompanies menopause. Women with uterine fibroids should have their blood estrogen level checked. If blood testing reveals too much estrogen, consider asking your doctor to prescribe a low dose (1 mg every few days) aromatase-inhibiting drug such as anastrozole (Arimidex®). By having a physician adjust the dose of Arimidex®, women may be able to lower excess estrogen, thereby helping to shrink fibroids and possibly reducing breast cancer risk. When Arimidex® was compared to tamoxifen in a breast cancer prevention trial, Arimidex® was slightly more effective and virtually free of side effects (ATAC Trialists' Group 2002).
Metformin Inhibits Uterine Fibroid Cell Growth
Metformin is the most frequently used anti-diabetic drug in the world (Li 2013). In recent years, studies have revealed that, in addition to its proven ability to regulate blood glucose levels, metformin possesses potent anticancer properties (Beck 2013). Metformin is thought to mitigate the growth of various cancers by activating an enzyme involved in cellular energy regulation called AMPK, which subsequently inhibits a molecular pathway involved in cell survival called mTOR, and through its ability to modulate insulin signaling (Beck 2013; Luo 2010; Hawley 2002).
Research published in 2013 suggests that metformin’s ability to oppose growth of malignant cells may also extend to benefits for women with uterine fibroids. In an experimental study, scientists measured the rate of proliferation of uterine fibroid cells following exposure to metformin. They found that “Metformin potently inhibited [uterine fibroid cell] proliferation in a dose-dependent manner.” The researchers then analyzed the molecular mechanisms by which metformin accomplished this powerful reduction in uterine fibroid cell proliferation. Their investigation revealed that this feat was mediated through one of the same pathways by which metformin suppresses cancer cell growth, namely the AMPK-mTOR pathway (Li 2013).
Given the widespread use of metformin and its generally excellent safety profile (Anonymous 2005), women with uterine fibroids – especially those with elevated blood glucose levels – should talk to their physicians about the potential benefits of metformin.